> But then you need to detect zero crossings

The MOC3041 is a ZC opto-triac, so if you're using an opto
anyway there's no added complication to the design

Cheap 4-pin opto-transistors can be used as ZC detectors too,
to detect one or both of the cycle peaks

http://home.clear.net.nz/pages/joecolquitt/txless.html

with a little s/w to get the actual timing spot on

Joe
--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.